Reduction of aliphatic halides containing functional substituents, such as carbonyl, cyano, and ether groups, by triethylsilane was studied in the presence of benzoyl peroxide at 80°C. It was found that those functional groups were not reduced under the conditions employed, and the only chemical reaction observed was the halogen-hydrogen exchange. Results also indicate that the reduction is accelerated in the presence of carbonyl and cyano groups, but is little affected by the ether oxygen. Relative reaction rates of some of those halides were determined by the competitive technique, and a linear free energy relationship was observed between the relative rates and the Taft σ constants of the substituents, with a ρ value of +0.30.